Cell Cycle Visualization Using Fluorescent Protein Markers

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Solution Overview

Problem

Current methods for analyzing cell cycle phases, such as the G1, S, G2, and M phases, are limited in their ability to perform real-time observations and struggle to distinguish between proliferation and resting phases effectively, particularly due to issues with gene expression visualization and transgene integration.

Innovation Solution

A method utilizing specific gene-expression products, such as partial fragments of Cdt1 and Geminin, labeled with different fluorescent markers, to visualize and distinguish between cell cycle phases in real-time, allowing for the use of a permanent promoter and localization of signals within the nucleus.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the G2M cell cycle phase marker is used to visualize a specific phase of the cell cycle, then the M phase and G2 phase can be detected, but the G1 phase cannot be visualized and the contrast is unclear

Engineering Contradiction:
Improvephase detection accuracyVSAvoidG1 phase visualization
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The cell cycle visualization is segmented into multiple independent fluorescent markers: Cdt1-GFP for G1 phase, Cdt1-RFP for S/G2/M phases, and Geminin-RFP for S/G2/M phases. This segmentation allows each phase to be visualized independently with appropriate contrast, resolving the limitation of the single-marker G2M system that could not detect G1 phase.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention employs color changes through fluorescent proteins to distinguish cell cycle phases. GFP (green fluorescence) indicates G1 phase when Cdt1 is present, while RFP (red fluorescence) indicates S/G2/M phases when Cdt1 is degraded and Geminin is present. This color-based differentiation provides clear visual contrast between phases, solving the contrast problem of the G2M marker.

Inventive Principle:
Principle #32Color changes

2Measurement precision

If promoter activity of cyclin is used for visualization, then cell cycle phase can be detected, but transformation by gene introduction is remarkably influenced depending on transgene integration

Engineering Contradiction:
Improvephase detection capabilityVSAvoidtransformation consistency
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The invention extracts the cell cycle detection function from promoter activity and transfers it to protein degradation-based fluorescent markers. By using Cdt1 and Geminin proteins with cell cycle-dependent degradation patterns, the system achieves phase detection without relying on promoter integration sites, thereby eliminating the transformation variability caused by different integration locations.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces Cdt1 and Geminin proteins as intermediary markers that mediate cell cycle phase detection. These proteins serve as reliable intermediaries because their degradation patterns are inherently cell cycle-dependent and不受transgene integration influence, providing consistent phase detection across different transformation events.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If cell synchronization and biochemical model are used for cell cycle analysis, then phase identification is possible, but real-time observation cannot be performed

Engineering Contradiction:
Improvephase identification accuracyVSAvoidreal-time observation capability
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The invention performs preliminary action by fusing fluorescent proteins to Cdt1 and Geminin before cell cycle progression occurs. This allows the fluorescent markers to be continuously present and report cell cycle phases in real-time as they naturally progress, eliminating the need for synchronization procedures and enabling dynamic observation of cell cycle events as they happen.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The fluorescent protein markers provide continuous useful action by constantly reporting cell cycle phase information throughout the cell cycle progression. Unlike synchronization methods that provide discrete snapshots, the fluorescent markers continuously indicate the current phase, enabling real-time tracking and observation of cell cycle dynamics without interruption.

Inventive Principle:
Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables real-time differentiation between proliferation and resting phases with high contrast, facilitating the study of cell cycle coordination with other cellular functions and simplifying the production of transgenic organisms.

Implementation Method 1

visualizing, by using a marker, at least one or more gene-expression products whose amounts in a cell change in a cell-cycle dependent manner

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Data Source

PatentEP2138577B1Probe for visualizing cell cycle
Publication Date: 2017.03.22 RIKEN CO LTD
  • EP2138577B1 patent drawingFigure 1
  • EP2138577B1 patent drawingFigure 2
  • EP2138577B1 patent drawingFigure 3A~3D

AI summary

An object of the present invention is to provide a method with which it is possible to easily distinguish a proliferation phase of a cell cycle from a resting phase thereof in real time. The object of the present invention is attained by providing a method for performing phase identification of the cell cycle, the method including: visualizing one or more gene-expression products as markers whose amounts in a cell change in a cell-cycle dependent manner; and detecting the products so as to distinguish the proliferation phase of the cell cycle from the resting phase thereof.